Sucralfate is a medicine that is described in the Japanese Pharmacopoeia and commonly used as a therapeutic for gastric and duodenal ulcers. The mechanism of its action is known to be attributable to antipepsin and antacid effects and the like. Two principal effects of sucralfate are believed to be forming a highly adhesive gel under an acidic condition to cover an ulcerated surface and in binding with plasma proteins under an acidic condition to cover the ulcerated surface (i.e., a mucosa protecting action). However, for selective binding to the mucosal ulcer site, the formation of a gel under the acidic condition caused by gastric acid is essential and in areas where acids are absent such as the small intestine, colon and the skin, no chemical binding and adhesion to the ulcer site occurs, except by physical adsorption.
There have been very few cases of the application of sucralfate which has been provided with enhanced adhesion to mucous membranes as in the small intestine and colon and the only exception is found in Japanese Patent Public Disclosure No. 190127/1987, which describes the application of added, collagen to the wound site. In known cases of sucralfate application to ulcerative colitis, sucralfate suspensions prepared with methylcellulose, propylcellulose and the like being added as thickeners are administered by the enteral route (see Scand. J. Gastroenterol., vol. 24, pp. 1014, 1989, Endoscopy, vol. 18, pp. 115, 1986, etc.) but these preparations have encountered several problems, one of which is that adhesion to the ulcer site is not expected.
As for the addition of organic acids to sucralfate, Japanese Patent Publication No. 35130/1993 describes the case of adding a phosphate or citrate to a sucralfate suspension. In this case, the organic acid salts are utilized to enhance the dispersibility of the suspension. However, enhanced adhesion to the ulcer site is not expected. Japanese Patent Domestic Announcement No. 500052/1993 discloses the technique of preparing effervescent tablets by adding an organic acid and a carbonate to sucralfate. However, the purpose of this proposal is the application of effervescent sucralfate tablets to the stomach and the use of carbonates is not intended to enhance the adhesion to the ulcer site.